In recent years, copper wire has been suggested as an inexpensive bonding wire that substitutes gold wire.
Patent Document 1 describes a bonding wire having a core material containing copper as a main component, and provided thereon, an outer coat layer containing a conductive metal and copper, which is different from the core material in terms of one or both of the component and the composition. In regard to this bonding wire, when the thickness of the outer coat layer is set to 0.001 μm to 0.02 μm, it is described that the material cost is low, and ball bondability, wire bondability and the like are excellent, so that the loop formability is also satisfactory, and then, a copper-based bonding wire which is also adapted to line thinning for narrow pitch applications, and diameter thickening for power IC applications, can be provided.